Abrasive Waterjet Polishing Research Articles

Nozzle Wear in Abrasive Water Jet Based on Numerical Simulation.

Particle diameters and jet pressure in abrasive water jet (AWJ) are significant jet properties which deserve a better understanding for improving AWJ machining performance. Some influence factors have been verified regarding nozzle wear in abrasive water jet polishing application. A three-dimensional model of a nozzle is established to analyze the influence of internal multi-phase flow field distribution, which is based on Euler-Lagrange methodology. With the increase of jet pressure, the erosion rate decreases; with the increase of the diameter and mass flow rate of the erosion particles, the erosion speed increases as well. When the diameter of the outlet is worn to 1.6 mm, the pressure on the work piece caused by the abrasive water jet increases by more than double compared to the non-worn nozzle; when the diameter of the nozzle outlet is worn to 1.6 mm, the shear force is 2.5 times higher than the shear force when the diameter is 1.0, which means that the jet force is divergent when the diameter is 1.6 mm, and the damage of the work piece is very serious. The obtained results could improve polishing efficiency on the work piece, extend nozzle lifetimes, and guide the future design of AWJ nozzles.

Abrasive water jet polishing of TBC blocked inclination holes on superalloys using an optimized nozzle

Abrasive water jet polishing of TBC blocked inclination holes on superalloys using an optimized nozzle

Optimization of the Morphology of the Removal Function for Rotating Abrasive Water Jet Polishing.

Abrasive water jet polishing has significant advantages in the manufacturing of complex optical components (such as high-slope optical component cavities) that require high-precision manufacturing. This is due to its processing process, in which the polishing tool does not make direct contact with the surface of the workpiece, and instead maintains a considerable distance. However, the removal functions of most existing abrasive water-jet polishing technologies do not possess strict symmetry, which significantly impacts the ability to correct surface figure errors. Therefore, this study implements rotating abrasive water-jet polishing based on traditional abrasive water jet processing to optimize the removal function, which turns it into a Gaussian form; thus, obtaining a type of removal function more suitable for CCOS polishing. This paper derives an empirical formula between the distance s' from the peak removal point of the removal function to the stagnation point and the nozzle tilt angle α, based on geometric relationships and experimental results, analyzes the relationship between material removal efficiency, nozzle tilt angle, and standoff distance. Finally, this paper verifies through experiments the validity of this empirical formula under different process parameters. Therefore, this study obtains the process conditions that allow rotating abrasive water-jet polishing technology to achieve a stable Gaussian form removal function, and the appropriate process parameters to be selected in conjunction with polishing efficiency; thereby, effectively improving the removal function's corrective ability and manufacturing efficiency. It provides theoretical support for the processing capability and process parameter selection of abrasive water-jet polishing technology, solves the problem of limited shaping capability of existing abrasive water jet tools, and significantly improves the manufacturing capability of high-end optical components.

A novel interpretable predictive model based on ensemble learning and differential evolution algorithm for surface roughness prediction in abrasive water jet polishing

A novel interpretable predictive model based on ensemble learning and differential evolution algorithm for surface roughness prediction in abrasive water jet polishing

Research on Abrasive Water Jet Polishing of Silicon Carbide Based on Fluid Self-Excited Oscillation Pulse Characteristics

A self-excited oscillating pulsed abrasive water jet polishing method is proposed to solve the problems of low removal efficiency in traditional abrasive water jet polishing and the influence of an external flow field on the material surface removal rate. The self-excited oscillating chamber of the nozzle was used to generate pulsed water jets to reduce the impact of the jet stagnation zone on material surface removal and increase the jet speed to improve processing efficiency. ANSYS Fluent was employed to simulate the processing flow field characteristics for different lengths of oscillation cavities. The simulation results indicate that the velocity of the jet shaft reached a maximum of 178.26 m/s when the length of the oscillation cavity was 4 mm. The erosion rate of the material is linear with the processing angle. A nozzle with a length of 4 mm of the self-excited oscillating cavity was fabricated for SiC surface polishing experiments. The results were compared with those of ordinary abrasive water jet polishing. The experimental results showed that the self-excited oscillation pulse fluid enhanced the erosion ability of the abrasive water jet on the SiC surface and significantly improved the material-removal depth of the abrasive water jet polishing SiC. The maximum surface erosion depth can be increased by 26 μm.

Theoretical Modeling Method for Material Removal Characteristics of Abrasive Water Jet Polishing under Rotating Oblique Incidence.

Abrasive water jet polishing (AWJP), as an ultra-precision machining technology, has unique machining advantages. However, the machining application of nozzles in vertical and inclined states is greatly limited because rotational symmetric material removal characteristics and the largest amount of central material removal cannot be obtained. At the same time, considering the many controllable and uncontrollable factors in AWJP, it is difficult to accurately model the removal characteristics obtained by machining. Based on the idea of the Preston equation and the calculation of fluid dynamics, this study first analyzed the material removal characteristics of a single abrasive particle and used FLUENT fluid simulation software to obtain the pressure and velocity distributions at different positions in the processes of nozzle rotation and tilt polishing. By analyzing the influence of the pressure and velocity distributions on material removal and the surface shear stress of the workpiece, a theoretical model of the material removal characteristics of abrasive water jet polishing under rotating oblique incidence was established. Finally, the effectiveness of the theoretical removal model was verified by comparing and analyzing experimental and theoretical results.

Research on Surface Quality of 38CrMoAl Polished Based on Abrasive Water Jet

Because the screw surface is slender and complex, it is difficult to process by traditional polishing methods. In order to improve the surface quality of screw, the abrasive water jet polishing (AWJP) technology was used to polish 38CrMoAl steel, which is commonly used in screw. The effects of different inlet pressure, target distance and abrasive particle size on surface roughness are analyzed. The experimental results show that with the increase of inlet pressure, the surface roughness first decreases and then increases. With the increase of target distance, the surface roughness first decreases and then increases. The smaller the abrasive particle size, the better the polishing effect.

Surface modification of Ti6Al7Nb employing pure waterjet and abrasive waterjet polishing for implant application: comparison study

Natural bones in vertebrates are replaced with implants when it fails under fatigue/impact loading conditions. The implants surface roughness is a vital parameter that enhances the osseointegration rate owing to mechanical stability by firm anchoring between the implant and the bone tissue. In this research article, surface modification of Ti6Al4Nb by the action of impingement erosion was executed under two conditions (i) Waterjet polishing (WP) without abrasives; (ii) Abrasive waterjet polishing (AWP) with biocompatible abrasives and studied in correlation to MRR and average surface roughness. The bio abrasives were made in a laboratory that endorses the bone healing characteristics availing 85% hydroxyapatite (HAp) and 15% yttrium stabilized zirconia. SEM, EDS, XRD, AFM and Non-contact surface roughness measurements were used to study the surface morphology of the bio-abrasives and the AWP surface. Experimentally the WP resulted in 73% more material removal rate and with higher average surface roughness Ra by 50% when compared to the AWP. The biocompatibility of Ti6Al4Nb post AWP was found to be favourable with more live cells after performing the MG63 Cell assay for the optimal exp run #11 obtained via the desirability function algorithm.

Insights of abrasive water jet polishing process characteristics and its advancements

Nowadays, Abrasive water jet (AWJ) machining is used in the manufacturing Industries as cutting, turning, milling and drilling processes. The application of this technology is further extended into polishing application. However, the cutting nature of the AWJ have produced the inappropriate surface conditions. Recently, the hybrid AWJ namely, Ultrasonic Assisted Abrasive Water Jet Polishing (UAAWJP) is mainly developed for polishing the complex shapes and the internal features of both metal and non-metals. Compared with other polishing technologies, UAAWJP has several advantages such as improvement in performance efficiency, higher kinetic energy, better surface quality, high precision, ease to control and absence of thermal distortions. The hybrid process is involved with variety of factors such as ultrasonic waves (frequency and vibration), abrasive particle type &size, jet pressure, traverse rate, abrasive mass flow rate, standoff distance, nozzle geometry, jet impact angle and processing time. However, the usage of conventional AWJ and UAAWJP techniques is scarce due to the lack of understanding of process mechanism and technical publications. It is mentioned that review article on AWJ polishing operations has not been published till date. Therefore, the present work is deals with the insights of previous studies on AWJ polishing and it advancements particularly in UAAWJP, and the results are presented with in view of process mechanism, features, benefits, effects and applications, and the results are also compared with other polishing techniques. The outcome of this study can also provide the better understanding and confident to the researchers and scientists on UAAWJP for further advancements and applications on it.

Experimental investigation on abrasive water jet polishing of stainless steel: a preliminary study

Abrasive water jet (AWJ) is a versatile machining technique for the production of components in various applications. In this paper, AWJ machining technique is extended to polishing operations on stainless steel 304. The polishing operations were carried out in the OMAX-AWJ machining centre by controlling the process parameters, namely, the traverse rate and the abrasive mesh size. The single and double pass roster method was considered for the production of polished surface by AWJ. In this study, in-depth analysis of 3D surface topography and surface morphology has been done on various polished surfaces. The experimental results indicated the yield of a surface texture with beneficial roughness features for the double pass jet operation through the employment of an abrasive mesh size of #300 and a traverse rate of 39.96 mm/min.

Experimental investigation on abrasive water jet polishing of stainless steel: a preliminary study

Experimental investigation on abrasive water jet polishing of stainless steel: a preliminary study

Evaluation on ultrasonic abrasive water jet surface processing of aluminum nitride

In the present study, the processing performance of ultrasonic assisted abrasive waterjet polishing was experimentally investigated by using response surface method. The experiment was designed with the application of Box-Behnken method. The second order multiple regression equations were established to acquire the response surfaces. The ANOVA results showed that impact angle, the second order term of pump pressure and the interactive term of impact angle and ultrasonic power are the most significant factors in affecting the surface roughness. The interactive effects on surface roughness of the processing parameters were investigated with the response surfaces. It has been found that better finish can be acquired at higher ultrasonic power as a consequence of the enhancement of the ductile removal ability in the abrasive erosion process. Finally, the processing optimization was conducted with the use of response surfaces. The results of the validation experiment positively verified the optimization and prediction capacity of the response surface model.

Experimental study on abrasive water-jet polishing of cemented carbide and polycrystalline diamond tools

This research paper studies the material removal mechanism, influence of water jet pressure and jet impact angle on the polishing effect of super-hard tools surfaces and edges experimentally. The results showed that the water jet pressure and jet impact angle have great influence on the materials removal efficiency. The jet angle of 15° and pressure of 10 MPa resulted in better-polished surface of the cemented carbide tools. The rake face of polycrystalline diamond cutting tools experienced no significant change under low pressure of 5 Mpa. Nevertheless, at a jet impact angle of 75° and a pressure of 20 MPa, the edge of the polished polycrystalline diamond cutting tool was bright, smooth, and rounded with 'ductile erosion micro material removal mechanism' without any fracture. The results demonstrated that the built abrasive water jet polishing technology system can be used in the super-hard tools industry to improve on the tool's services life.

Experimental study on abrasive water-jet polishing of cemented carbide and polycrystalline diamond tools

This research paper studies the material removal mechanism, influence of water jet pressure and jet impact angle on the polishing effect of super-hard tools surfaces and edges experimentally. The results showed that the water jet pressure and jet impact angle have great influence on the materials removal efficiency. The jet angle of 15° and pressure of 10 MPa resulted in better-polished surface of the cemented carbide tools. The rake face of polycrystalline diamond cutting tools experienced no significant change under low pressure of 5 Mpa. Nevertheless, at a jet impact angle of 75° and a pressure of 20 MPa, the edge of the polished polycrystalline diamond cutting tool was bright, smooth, and rounded with 'ductile erosion micro material removal mechanism' without any fracture. The results demonstrated that the built abrasive water jet polishing technology system can be used in the super-hard tools industry to improve on the tool's services life.

Evolution of White Layer during Wire-Cutting and Comparison of Several Methods to Improve Surface Integrity for Fineblanking Tools

Powder metallurgical high speed steel (such as S390) has superior mechanical properties and been used as fineblanking tools. The electrical discharge machining has been widely used for cutting fine blanking tools which are made of especially hard tool steels. Whereas, its thermal nature causes great concerns regarding surface integrity, which matters a lot to tool life. In the present study, the evolution of surface integrity of the S390 with multi-cutting is comprehensively compared. The result shows that the surface roughness, white layer thickness and surface residual stress decrease with the increase of cutting pass. Additionally, the effectiveness to remove white layer on HSS S390 by manual and towed polishing and electrolytic polishing are compared. At last, a device of abrasive water jet polishing is designated to remove the white layer resulted from wire-cutting.

A review on recent advances in machining methods based on abrasive jet polishing (AJP)

Abrasive jet polishing (AJP) is a new non-conventional machining technology for applying to polish the complex surfaces and small areas. Compared with other polishing technologies, AJP has the following advantages: high precision, easy to control, small machining force, good flexibility, without thermal distortion, etc. A review of five main AJP technologies has been conducted to provide an insight into the trends in research of principles, technological method, and impact of polishing quality. Several AJP methods discussed in this work include abrasive water jet polishing, nanoparticle colloid jet polishing, magnetorheological jet polishing, abrasive air jet polishing, and negative pressure cavity jet polishing. The monitoring methods of AJP process are introduced. The jet velocity, material removal, surface roughness, and numerical modeling of jet polishing are also discussed. The effects of some major technological parameters are analyzed. The polish results of metal, glass, and silicon materials are summarized. The probable further research tendency on AJP technology is forecasted. It is a high-potential technology to machine the microstructures and difficult-to-machine materials.

A 3D simulation of the fluid field at the jet impinging zone in ultrasonic-assisted abrasive waterjet polishing

In the present study, the fluid field of the impinging jet on the workpiece surface in ultrasonic abrasive waterjet polishing (UA-AWJP) was simulated. The influences of the workpiece vibration on the pressure and velocity field of the impinging jet fluid field at the stagnation zone and the side flow zone were investigated. The impinging force on the vibration workpiece surface was experimentally measured. The results illustrated that, in the case of workpiece vibration, the stagnation is weakened due to the shearing action at the boundary layer and the impinging velocity is lower. Meanwhile, the velocity magnitude with asymmetric distribution is higher. The force fluctuation in the case of workpiece vibration is obviously stronger, while the mean value of the force is lower than that of the non-vibration condition. The measured data was in reasonable agreement with the simulation results.

A Study on Ultrasonic Torsional Vibration-Assisted Abrasive Waterjet Polishing of Ceramic Materials

Abrasive waterjet machining is considered as a promising technique in hard-brittle material polishing. In this paper, The ultrasonic torsional vibration is considered to apply on the workpiece to improve the abrasive waterjet polishing quality and efficiency. The process parameters in the ultrasonic torsional vibration-assisted abrasive waterjet polishing are optimized. The ultrasonic torsional vibration in the role of the abrasive waterjet polishing is investigated. The results show that the application of ultrasonic torsional vibration can effect of abrasive particle movement and increase the critical depth of the ceramic materials.

A research on ultrasonic-assisted abrasive waterjet polishing of hard-brittle materials

In the present study, the abrasive waterjet (AWJ) with the aid of ultrasonic vibration was used to improve the processing performance of hard-brittle materials. The method is termed as the ultrasonic-assisted abrasive waterjet polishing (UA-AWJP). Aluminum nitride was chosen as the workpiece material. Ultrasonic vibration perpendicular to the jet impact direction was applied on the workpiece by using a specially designed stage. A series of experiments were performed to evaluate the performance of the UA-AWJP. The processing performances and the polished surface topographies of the AWJP and UA-AWJP were compared to investigate the effects of ultrasonic vibration. The results show that UA-AWJP has a higher processing efficiency than AWJP. The surface roughness of the polished surface was modeled. The model shows a considerable agreement with the experimental results. The experimental results show that a lower pressure, finer abrasives, and a smaller impact angle are ideal to obtain a high surface quality.

Uniform scanning path generation for abrasive waterjet polishing of free-form surfaces modeled by triangulated meshes

In this paper, a method is proposed to generate scanning paths to be used in automated abrasive waterjet polishing of free-form surfaces. This method is able to produce trajectories with constant offset distance between curves on surfaces with holes and complex boundaries without reconfiguration of their triangular mesh model. For this, the particular requirements of this polishing technique to be kept along the path are investigated. Next, a reference curve is obtained and using geodesic distances in specific directions, the adjacent offset curves are found. Finally, if needed, the main trajectory is divided into a set of continuous sub-trajectories. By defining two indices, the effect of the shape of the surface and the configuration of the generated path on the uniformity of the distribution of the waterjet is evaluated. Through several examples, it is shown that the method can effectively generate scanning paths adapted to the requirements of this technique.